1. Field of the Invention
The present invention relates to corrosion inhibiting aqueous media for use in steam generator applications and in particular relates to the use of activated boric acid compounds for inhibiting carbon steel corrosion in the secondary system of nuclear steam generators.
2. The Prior Art
The use of boric acid for preventing or at least inhibiting carbon steel corrosion in the secondary water systems of nuclear steam generators has been known for sometime. In particular, boric acid has been utilized to minimize the phenomena known as denting at the tube/tube support plate interface in nuclear steam generators. A full report of the use of boric acid for such purposes is contained in a publication entitled "Implementation of Boric Acid in the Field-Indian Point Unit 3 Plant" prepared by Westinghouse Electric Corporation, Nuclear Technology Division for Steam Generator Owners Group and Electric Power Research Institute. Copies of this report are available through Research Reports Center, Box 50490, Palo Alto, Calif. 94303. While boric acid alone has been found to be highly useful for inhibiting carbon steel corrosion of the type which results in denting, nuclear applications require a continuous search for improved systems and increased reliabilities. Diol boric acid compounds which are more strongly acidic than boric acid alone are known from such prior publications such as an article entitled "On the Composition of Acid Boric Acid-Diol Compounds", J. Boeseken and N. Vermaas, J. Phys. Chem., 35, 1477 (1931) and an article entitled "Volatile Borates of Polyhydric Alcohols and the Activation of Boric Acid", R. E. Rippere and V. K. La Mer, J. Phys. Chem., 47, 204 (1943). These articles discuss the reactions between boric acid and diol compounds to activate boric acid by producing diol boric acid complexes which have more acidic characteristics than does boric acid itself. However there is no suggestion in the prior art that such diol boric acid complexes are capable of inhibiting corrosion. And even more so there is no disclosure that diol boric acid complexes might be useful for inhibiting carbon steel corrosion in nuclear steam generator applications.